Tailored hybrid materials for biodiesel production: Tunning the base type, support and preparation method for the best catalytic performance

• Published in: Molecular catalysis 2018-10, Vol.458, p.240-246
• Main Authors: Lima, Ana Lúcia de, Vieira, José S.C., Ronconi, Célia M., Mota, Claudio J.A.
• Format: Article
• Language: English
• Subjects: Base catalysis; Biodiesel; MCM-41; Transesterification
• ISSN: 2468-8231; 2468-8231
• DOI: 10.1016/j.mcat.2017.09.032

[Display omitted] •TBD and 3-aminoquinuclidine grafted on MCM-41 were synthesized by co-condensation.•TBD and 3-aminoquinuclidine grafted on silica gel were synthesized by post-synthesis.•TBD-based catalysts presented higher yield of biodiesel due to the higher basicity.•TBD-MCM-41 prepared by co-condensation showed a lower deactivation rate than the same catalyst prepared by post-synthesis.•The lower deactivation rate may be related with a better dispersion of the base on the catalyst prepared by co-condensation. Hybrid materials were prepared by the functionalization of mesoporous silica MCM-41 with 1,5,7-triazabicyclo [4.4.0] dec-5-ene (TBD) and 3-aminoquinuclidine (3AQ) by the co-condensation method, resulting in the heterogeneous catalysts MCM-41-TBD, MCM-41-3AQ. Silica gel was also functionalized with TBD and 3AQ using post-synthetic method upon the reaction with 3-chloro-propyl-triethoxy-silane and then, undergoing nucleophilic substitution with TBD or 3AQ, resulting in SG-TBD and SG-3 AQ, respectively. The successful anchoring of the organic bases on the silica supports has been shown by 29Si MAS/NMR and elemental analysis (CNH). The ordered structure of the MCM-41 support was damaged upon base functionalization. The heterogeneous catalysts were tested in the transesterification of soybean oil to produce biodiesel. MCM-41-TBD catalyst converted 100% of the soybean oil to biodiesel within 2h at 70°C, whereas the other catalysts required more severe reaction conditions to achieve conversion in the range of 24–98%. The catalysts based on grafted TBD, regardless of the type of silica used, were more active than those based on 3AQ, because of the higher basicity of the former amine. The MCM-41-TBD presented slower deactivation rate, upon reuse, compared with the same material prepared by post-synthetic methods The possible explanation is related with the higher incorporation of the base on the silica support by the co-condensation synthetic method as well as its more uniform distribution on the catalyst surface.